1. Field of the Invention
This invention relates to a multiple heat-sensitive copying medium, and more particularly to a multiple heat-sensitive copying medium adapted for use in the heat-sensitive recording system.
2. Description of the Prior Art
A nonimpact system has been recently developed in the field of recording in the data communication such as a facsimile, an output of a computer and the like. The most important advantage of the nonimpact system resides in that a noise annoying operators can be eliminated to a great extent and this nonimpact system is characterized by "a gentle print recording system". A heat-sensitive recording sheet is also used as one of the media in the nonimpact system. However, a practical disadvantage of the heat-sensitive recording sheet as well as the nonimpact system is that simultaneous copying is extremely difficult, and more particularly that the same plural records can be hardly obtained simultaneously by using one recording element, which is a heat element in a heat-sensitive recording system. As for such a heat-sensitive recording sheet as takes a printing time of only about 10 milliseconds, if two conventional heat-sensitive sheets are put one upon the other and printed by applying a thermal printer to the top one of the two heat-sensitive recording sheets, it would be so difficult to color-develop the bottom recording sheet that the same two records can not be obtained simultaneously.